I'm sitting here in paradise assembling this blog that Dennis wrote - but it is NOT paradise because the roar of the generator is disturbing my peace! Why is the generator running? It has to run for about 3 hours to charge up the batteries for the caretake's cottage after 5 days of cloudy weather. The big solar system that powers our cabana is still doing fine, but the smaller one on the caretaker's cottage is not as robust. Now I remember why getting on solar was such a big deal for us! Switching over to solar really was the end of the world as we knew it, and now we have a better world here in South Englishtown. Without further ado, I turn this over to Dennis to take you through the Final Installment.
It’s the End of the World as We Know It (click to watch and listen. BTW- R.E.M. is from Athens, Georgia, where Dennis and I met at the University of Georgia back in the 1980s.) This Final Installment deals with having the Pro’s come and install the solar power system, and adding in some insurance measures to minimize risk of catastrophes. Also it deals with changing from a diesel generator "alarm clock" going off at dawn each day to the gentle hum of a solar system.
Installation of the Panels, Batteries, and Hardware: Bringing in the Pro’s. And we don’t mean Mr. O’Reilly of Fawlty Towers fame from our previous solar blog. Once you do all the calculations, check that these match up approximately with all the results from the various methods tried, then it is time to get the professional solar installer involved.
Why bring in an installer when we have done so much ourselves? This was best explained to me by Craig Pearlman, our neighbor and owner of Barebones Tours - check it out and learn about “Percy the King of the Howlers”! I had complained to him that I was not able physically to do the things I use to do for repairs and maintenance. He said that I shouldn’t be doing the things I use to do. That I was older and retired and should obey the Englishtown Prime Directive: Do Not Get Hurt!!! This is especially true when you are past retirement age, when you do not heal and recuperate as well as when younger. I could get hurt trying to install the solar panels myself, falling off the steep 32degree roof that is 30 feet or so above the ground for example. Bummer. Although growing old takes its toll, with age also comes the hard won wisdom to leave the physically demanding jobs to the younger fellows with the proper equipment.
In our case we used ProSolar Engineering Ltd. in Belmopan. Marco Valle, the Principal, has an electrical engineering degree and 20+ years experience working on solar installations, mostly in Belize. He had worked on our place before for a couple of projects including the trial installation of 9 solar panels on the Caretaker Cottage in April of this year. He looked over the calculations and agreed with them, and then he put together the hardware we needed.
We decided on using 2 inverter/chargers with 2 separate charge controllers, and then single modules for control and communication (Outback) set up in a Master/Slave configuration. This would permit generating up to 6000 watt.hours of electricity if needed, and also permit having some redundancy in case one unit failed.
The inverter/chargers’ roles are to charge the battery bank using the DC output from the solar panels. They also allow for an AC input from a generator or other source for charging the batteries, changing the sine wave of AC to the flatline DC output (the process of inverting from one electric form to another). Finally, they take the flatline DC output from the batteries and invert that to AC for running the appliances and lights in the cabanas.
The two inverter/chargers had to be gasket-sealed units due to the sea water spray-induced corrosion here. Over a period of 6 pre-solar years, we had lost 3 Xantrex Freedom 30 Marine non-sealed inverter/chargers due to corrosion.
The inverter/chargers, charge controllers, and all the other ancillary pieces of hardware and cables were imported by ProSolar from Outback Power and the system assembled on site by the crew. This is similar to the Outback FlexPower 2 integrated system minus a few bells and whistles we did not need.
The ProSolar crew of 3 technicians came down in mid-June and spent 3 ½ days installing the panels, cabling the batteries, and installing all the hardware modules (inverter/charger, charge controllers, etc.) and programming the system so the batteries do not get overcharged. They also installed a lightning arrestor system. We put them up in a place in the village where they also had breakfast and dinner, and ordered in lunches for them from a good friend and cook in the village Elna Zuniga of Monkey River EcoTours.
|ProSolar crew getting the first row of panels mounted on the south-facing roof.
They had some problems in the mornings since there is dew on the roof and until the sun dries it out it is too slippery to work on. They also came at the very peak of Dr. Fly Season (see previous Glue Ball posts). The flies were relentless despite having glue balls up everywhere.
The hard part for me was sitting back during the installation with the nagging thought lurking in the back of my mind: despite all the checks and the reassurances, what if I did it wrong, what if I miscalculated? This is a once in a life-time event, could I have eff’ed it up?
But you can let go of those anxious feelings that perhaps you overlooked something critical and breath a sigh of relief once the lights come on, the fans run, and there is no electric crackling sound and no smell of smoke from burning wire insulation! OK photons, do your job!
“But remember, paradise doesn't come without a price” (from a lyric by Jimmy Buffet and Herman Wouk “Don’t Stop the Carnival”, thanks to my niece Kim for this citation).
Green ain’t cheap, over US$52,000 for what we did. Normally you have the cost of the hardware, transport, programming, and installation. However, we had some additional costs. We had to pay for International Shipping, customs duty imposed by the Government of Belize (up to 37% on the batteries and panels!), and delivery to us at the dock on the Monkey River, roughly US$10,000 combined extra expenses.
Panel Shipping to FL
Panel Ship to BZ + Customs
Batt Shipping to FL
Batt Ship to BZ + Customs
Equipment and Installations
Spare equipment/accessories $6,756.38
If you read the characteristics for choosing a home owner PV system (minus batteries) at Solar Panel Comparisons one of their acceptance criteria was cost per watt no more than US$3.94 for the equipment only. This would correspond to a grid-tie system in the US where there still is municipal electricity provided to the home and solar cuts down the electric bill. There is no battery system for storage. When we only consider the equipment used, less the batteries, we come out at US$3.24 per watt. Not bad. If all costs are considered, it is US$12.69 per watt – ouch! Going Green costs a whole lotta Greenbacks.
How long will it take to recoup our investment? If we consider the US$500 per month we were paying for diesel fuel, it would mean around 105 months to achieve payback or roughly, 8 3/4 years under the best of circumstances, not including all the other terms required in a Financial Effect Analysis (you know, opportunity costs, amortization, residual value, and so on). But it means 8 3/4 years of not having to constantly listening to a generator running, starting around 6 AM. We will have the diesel generator backup for cloudy periods, and a Briggs and Stratton gasoline generator as the backup for the backup in case of a solar power failure or hurricane, so we should be set. The solar system is expected to last about 20 years, so overall it should be cost effective. (Hey Dennis - I don't think you included the cost of getting the diesel to our place or the upkeep on the big generator. I think we may recoup the expense a little sooner.)
Could we have done this less expensively? Yes, about $15,000 cheaper, and cheaper still if we used lower quality panels and less robust batteries. But that would mean replacing batteries every few years and not having back-up hardware modules on site, meaning no redundancy for this remote site. It cost about US$6700 to have the redundancy of hardware modules we wanted for ease of rapid repairs. Each trip by ProSolar is billed at US$600 per day plus parts, so it would not take too much to add up to US$6700 in service fees, in addition to the inconvenience factor of waiting for them to be free to come down for the repairs.
Solar “Insurance”. We just spent over US$52K getting the solar systems here and installed. Wilma and I have always lived a very modest lifestyle, enabling us to save up to install this system as part of our dream retirement in Belize. This is a once in a lifetime project and we need to protect this investment. I am now 67 years old, and I don’t think I have it in me to do this again. We addressed the 4 areas where we have potential issues that might undermine the viability of the solar system.
First, we are in a high lightning strike area.
Second, there are potentials for fires starting due to salt corrosion on conductor connections and sparking since we live about 60 feet from the Caribbean Sea.
Third, we have a remote location and therefor we are a long distance from any support, so we need a high degree of self-sufficiency or be willing to pay for service calls.
Fourth, the system will only last if it is maintained properly and routinely.
Let’s take a quick look at these 4 big risks individually.
Lightning. Lightning does strike objects here, routinely blowing things up. It has exploded and splintered wooden poles carrying electricity to the local village a few times since municipal electricity was run to the village in 2009. It struck and exploded a palapa bar (a palm thatched platform) situated at the end of a dock about ½ mile south of us (that was definitely the last call for alcohol!)
Damage from lightning does not have to be from a direct hit. The lightning itself induces electric currents that can damage the electrical equipment. Our neighbor, Chris Harris, lost a charge controller (~US$560) on his solar system probably due to an induced current in a solar panel cable that likely acted as an antenna, carrying high voltage to the charge controller. About 4 days after our system installation, we had an intense series of four very near cloud-to-cloud lightning strikes that took out our satellite internet modem temporarily. A neighbor ½ mile North of us also lost his internet system as well. The solar power system is still functioning however.
You pretty much know if you have a direct hit from lightning (duh!), in some cases from the wood splinters decorating the road or burnt palm thatch floating on the sea. How do you know if lightning is causing induced electric currents? We had some experience with the first generation compact fluorescent light bulbs while living in Minnesota. When there was a nearby lightning strike, the bulbs would give an audible click and attempt to light up, and Max the Cat would make unpleasant grumbling noises. Now days, I look to see what Wilma’s Fit-Bit is doing when there is a lightning flash. If it flashes green after lightning, I know there was an induced electrical field. Similarly, we have LED solar lamps that also light up briefly when there is cloud to cloud or a lightning strike nearby.
We have taken a two-fold approach to minimizing the risk of lightning damage. We first have put up lightning rods and have grounded the electrical systems. This takes care of any direct hit as much as is feasible. The satellite dish was not grounded by the installer and the lightning possibly resulted in the satellite modem receiving high voltage. Furthermore we have placed surge protection devices on the DC and AC components of the solar system, and in the AC breaker boxes. These are rated above the estimated current of a lightning strike (115,000 amp capacity vs lightning estimated at 10,000 amps).
To mitigate risk for induced electric currents, we have put the solar system equipment, other than the solar panels, in “Faraday Enclosures”. Faraday boxes, cages, rooms, etc., minimize currents by surrounding the electrical components with a metal shield that absorbs the electric current. See more on constructing Faraday boxes here, especially if you want your computer to survive the nuclear holocaust (although the internet might not!). (Wikipedia has a very interesting article on Faraday Cages - be sure and read the "Examples" section to learn about "booster bags" for shoplifting and performers at Burning Man using Faraday Cages.)
In our case, the ‘Inverter Room”, which houses all the solar electrical equipment, has aluminum covered thermal insulation and wire mesh screening in the walls, ceiling and floor. It will be added onto the door entrance next. This acts as a shield, although somewhat imperfect, to minimize intrusion from lightning induced currents, and hopefully will minimize the risk for equipment damage.
The batteries are housed in a wooden battery box which also has wire screening in the floor, sides and top. The electric cable conductors leaving the box are wrapped in wire mesh and placed inside conduit that enters the Inverter Room and is connected to the wire mesh there. This needs some additional work at this time to make it secure - because the cell phone rang ! (see below).
But how do you know this will work? An equipment failure after a nearby lightning strike validates the insufficiency of protection. It is easy to tell if doesn't work, but harder to know if it actually protected the equipment or you just lucked out this time. Maybe the lightning strike did not induce sufficient current to cause equipment failure but the Faraday enclosure was inadequate as well. Short of a nearby strike, put a cell phone in the Faraday enclosures and see if it rings when its number is called (cell signals are radio waves). If it does ring, you need to do some additional work to reduce electric field and radio wave intrusion, as is the case for the battery box. This is still a work in progress and time will tell how well this works. (Note Added: since writing this in late Summer, I finally found the distribution of electric frequencies generated by lightning strikes. What does frequency have to do with all this, why the concern? Lightning-induced radio wave frequency relates to how small a metal mesh you need to use to block this energy: the higher the frequency, the smaller the mesh and gaps in the enclosure have to be. Most of the lightning energy is in the radio wave band area of 3 to 30 kilohertz, decreasing in intensity through the shortwave radio bands, and dwindling in intensity to about 1 gigahertz, which is about half the frequency of the cell phone service we use. So the cell phone test may be too stringent for lightning induced currents.)
One issue I have is the straight runs of cables from the solar panels. These look like long antennae inside plastic conduit to me. I asked an electrician about this and he did not think we needed metal conduit. He had worked on cell towers quite a bit and said it was not necessary from what he had seen and tested. But I may change this out. After all, Chris Harris lost that charge controller with the cause attributed to a solar panel cable acting as an antenna for a lightning induced electric current. Better safe than sorry. But we have other things to tend to first.
Fire!!!! The second issue is fires. Equipment shorting out, sparking from corroded connectors and wires is a significant risk in wooden structures, such as what we have, especially in the corrosive marine environment. Here is an image of what can happen. The fire in this breaker box occurred for other reasons, but the outcome would be the same.
We have taken several approaches to minimize and contain fire damage. First, the Inverter Room and the Battery Box are lined with plycem, a fiber reinforced cement board that has a good fire rating. The Inverter Room has, starting from the exterior: wooden siding and metal roof; aluminized thermal insulation; wire mesh Faraday shielding (i.e window screen); and plycem. The plycem encases the inside of the Inverter Room. The same is true for the Battery Box. The wall cavity housing the Main Load Center, the breaker box inside the new cabana, also is lined with plycem and fire stops are placed between the studs in the walls of the cabana to prevent vertical travel of a fire.
Furthermore, we have installed fire alarms inside the Inverter Room and cabana. Finally, we have two 10pound carbon dioxide fire extinguishers. The nozzles will be inserted into the inverter room and battery box. We would not have to open the doors to extinguish a fire. Opening a door would introduce more air with oxygen, just stoking the fire. We will just have to pull the pin and squeeze the handle on the extinguishers for fire control. Carbon dioxide extinguishers were chosen since there is no mess to clean up afterward on the electronics, unlike the less expensive chemical fire extinguishers.
One final item to note. The lead-acid batteries, including those purchased from Surrette, will generate hydrogen gas from water during the final stage of charging. If there is a spark, there could be an explosion and fire in the battery box. We replaced the caps that came with the batteries, and fit into each battery cell, with special caps that minimize the potential for sparks to cause an explosion.
|The yellow caps with green centers are the water miser caps that minimize the chance of sparks.
Living Remotely. We live about 1 mile by boat up the coast from Monkey River Village, which is at the end of 12 miles of unpaved, dusty, or muddy road, depending on the season, and which floods many years rendering it impassable for weeks at a time. From there, the nearest hardware store is about 8 miles via paved road. More precisely, we live at the “Arse-Back of Nowhere”. What this means, practically, is that if a component in the solar system fails, we may have to deal with it ourselves. Belmopan, where ProSolar Engineering is located, is 102 loooong miles away. They may not be able to come down here quickly for an emergency visit. To facilitate our capabilities to deal with problems, we have to have spare parts on hand. These include a “spare”: inverter/charger; charge controller; communication manager to connect the various pieces of solar equipment; a programmer module for the system; charging meter; surge protector devices for AC and DC equipment; and external fan for the inverter/chargers. Then there is the spare battery, cables, and so on. While we might be able to get these from ProSolar, there is no guarantee they will have them in stock when needed in an emergency. They can only carry so much in terms of parts at a time. So we need to be self reliant for the simple things. If a component goes bad, and has to be removed, we can wire a new one relatively easily.
Maintenance. This is the most boring part of it all but may keep the system alive for many years. There are two main areas that require occasional maintenance. The inverter chargers are sealed units, and have an external fan to cool them down. The fan can become clogged with dust that has to be removed or the fan may lock up and not cool the inverter. The fan cover is held on with 4 screws, remove it carefully and clean out the accumulated dust, without pulling the very fine wires out of the plastic connector!
The second area is battery preventive maintenance. The batteries need to be cleaned and inspected for corrosion every month. Distilled/deionized water is to be added as required. In addition, the battery electrolyte (battery acid) needs to have the specific gravity (SG) determined using a hydrometer. The SG indicates the level of charging or undercharging. The ideal SG for a completely charged battery is 1.265 g/cm3. If the specific gravity of the battery cells is low, then a maintenance procedure called “equalization” may have to be performed. When batteries are cabled in strings, some batteries may not be charged as efficiently as the others. Equalization takes care of this and also corrects stratification of the battery acid electrolyte. After fully charging the batteries by the sun, an AC power source, provided by a generator in our case, is used to further charge the batteries at a slightly higher voltage than usual. A program in the inverter/charger system selects the higher voltage used. The temperature of test cells is monitored with an IR hand-held thermometer (about $30 US) to detect overheating as well as by determining the SG with a hydrometer. Once the test cells reach an SG of 1.265 g/cm3, the equalization is continued for another hour to ensure no further change and then the program is stopped. The first time I did this after battery installation, it took 6 hours of charging with the generator to equalize the batteries.
Final Thoughts. If I had to do it all over again, I would have taken an easier path. Although I had read a number of articles and a book on solar power, what I had to do practically really did not sink in. Fortunately, there is much more information online today than when I started on this project, and much easier to get access to it.
Here is where I would go if I were going to still select components, but not do the actual installation: remember the Englishtown Prime Directive – Do Not Get Hurt!!!
First, determine the siting of the panels so they face True South. Determine if there is a significant discrepancy between True South and Magnetic South, doing it the easy way by finding the magnetic declination for your site online . Then decide if the panels will be mounted on the roof or in racks on the ground and inclined at what angle for your location.
Second, perform an electricity audit to see how much electricity you need to get from solar power. There are forms for this online here, here, and here.
Third, determine the battery type and capacity using online calculators provided at a number of solar vendor sites here, here, here, and here to name just a few.
Fourth, determine the number of panels required based upon your choice of panel wattage, again using online calculators.
Fifth, decide upon a solar installer to perform the actual installation and system testing (unless you really want to get down into the finer details of solar installation that have not been discussed here). The installer should also be responsible for dealing with any local ordinances and permits required (well in the Civilized World at any rate). You should also discuss the hardware components (inverters, charge controllers, etc.) that you will want to have in the system.
Yup, that’s pretty simple.
You can of course dive deeper into this, if you plan to calculate conductor sizes and things like that. I suggest you do a great deal of reading before you take this plunge however. A mistake could be catastrophic.
So that is the story behind the solar infrastructure that will permit Wilma to keep providing those wonderful Nature and humorous blog posts (the June 25, 2015 Iguana and Night Heron blog for example). Aww - thanks, Dennis. :-)
I certainly do not view myself as an expert on solar power, more like a somewhat knowledgeable novice (meaning potentially dangerous). So if you have suggestions for what we can do better, how to improve the system, and especially cautions and suggestions about safety, please let us know.
For whom does the inverter/charger fan hum? It hums for me. And now I’m just going to kick back and listen to that hum and watch the sugar-crazed hummingbirds fly about. One of them whapped me on the head with its wings not too long ago when I got too close to the feeder.
Wilma again. Dennis - my head is spinning. I am so glad you were in charge of making this happen. I am going to simplify the rationale for going solar for our readers.
- Municipal electricity is not available now or in the foreseeable future.
- Generators are noisy and somewhat expensive.
- I like my creature comforts (fridge, lights, fan, sewing machine, clothes washer, music, computers, running water) that require electricity.
- I like my peace and quiet in this very remote location.
- Solar is the only way to get what I want.
Like the iguana sunning itself in the photo below, we are green and enjoying the end of the world as we knew it and we feel fine in our peaceful paradise.
|Male green iguana in the buttonwood tree.